Volcanology Concepts Quiz

The tendency of a material to resist flow.

A type of magma with less than 50% silica, resulting in low viscosity and quiet eruptions.

The amount of silica in magma directly impacts its explosiveness and viscosity.

Dissolved gases, like water vapor and carbon dioxide, play a crucial role in determining a volcano's explosiveness.

The process of minerals in the mantle melting at high temperatures due to the presence of water vapor.

The physical property that describes a material's resistance to flow, influenced by temperature and silica content.

A type of magma with a high silica content, leading to high viscosity and explosive eruptions.

The type of volcanic rock formed when lava cools depends on the silica content of the magma.

The degree of violence or force with which a volcano erupts.

The composition of magma, including its silica content, influences how easily it flows. High silica content makes magma thick and sticky, leading to explosive eruptions.

The temperature at which rocks melt depends on their composition. Most rocks melt between 800°C and 1200°C.

Pressure increases with depth due to the weight of overlying rocks. This increased pressure raises the melting point of rocks, preventing them from melting in Earth's lower crust and upper mantle.

The presence of water and dissolved gases lowers the melting temperature of rocks, contributing to magma formation.

Understanding the factors that control magma behavior helps scientists predict the eruptive style of volcanoes.

Magma that solidifies beneath Earth's surface creates features like batholiths, stocks, sills, and dikes.

Lava is molten rock that erupts onto Earth's surface. Its flow is influenced by its viscosity, determined by its composition.

Andesitic magma is found along oceanic-continental subduction zones and contains 50 to 60 percent silica. The source material can be either oceanic crust or oceanic sediments.

Andesitic magma has a higher silica content, giving it intermediate viscosity. This results in volcanoes with intermediate explosivity.

Rhyolitic magma is formed when molten material mixes with silica-rich continental crust. It's rich in silica, containing over 60 percent.

The high viscosity and trapped gases in rhyolitic magma lead to very explosive volcanic eruptions.

Magma's temperature, silica content, and gas content determine its properties and how it erupts.

Plate tectonics and hot spots cause magma to rise and mix with the Earth's crust, leading to variations in its properties.

Magma has a higher viscosity when it has a higher silica content. This means it flows more slowly.

Trapped gases within magma can cause explosive eruptions, especially in cases like rhyolitic magma with high gas content.

Volcanic eruptions where lava is too thick to flow readily, causing pressure buildup and an explosive release of lava and rock fragments.

The material ejected from a volcano during an eruption. Includes ash, cinders, and larger rock fragments.

Fine volcanic dust with a diameter less than 2 mm that results from explosive eruptions.

Large rock fragments, greater than 64mm in diameter, ejected during volcanic eruptions.

Fast-moving, destructive clouds of ash and hot gas that travel down the slopes of volcanoes at speeds of about 80 km/h.

A large underground body of solidified magma that formed when molten rock intruded into pre-existing rock.

The process of magma rising towards the Earth's surface

When magma forces its way upwards through the Earth's crust, it can create fissures or cracks, then solidify into rock.

Intrusive igneous rock bodies formed during mountain-building and oceanic-oceanic collisions, often exposed at Earth's surface due to uplift and erosion. They can be various sizes and shapes.

The largest type of pluton, irregularly shaped, covering at least 100 square kilometers and formed over millions of years. Often found in the heart of mountains.

Similar to batholiths but smaller in size, also irregularly shaped. They are often found at depths ranging from 5 to 30 kilometers.

A lens-shaped pluton with a round top and flat bottom. Relatively small compared to batholiths and stocks, often less than 16 kilometers wide.

A type of pluton that forms when magma intrudes parallel to existing rock layers.

A type of pluton that cuts across existing rock layers, forming when magma intrudes cracks in surrounding rock bodies. They are often seen near volcanic conduits, but not always forming the neck.

A pluton that forms when magma cools within a volcanic conduit. It marks the former pathway of magma to the surface.

The cooling of magma within the earth's crust can form large bodies of igneous rock. These masses are called plutons and can vary greatly in size and shape.

The texture of a pluton can provide clues about its formation. Coarse-grained plutons indicate slow cooling deep within the crust, while fine-grained plutons suggest rapid cooling closer to the surface.

Plutons often form during mountain-building processes. Batholiths, large plutons, are frequently found at the core of mountain ranges.

The formation of batholiths is linked to collisions between continental plates along convergent boundaries. The immense pressure can cause the crust to melt and form plutons.

Plutons can also form from oceanic-continental convergence. The sinking oceanic plate releases water, which causes the overlying mantle to melt. This melt rises and cools, forming plutons.